a. Field of the Invention
The instant disclosure relates to a system employing a medical device, such as, for example, a catheter, for diagnostic, therapeutic, and/or ablative procedures. More specifically, the instant disclosure relates to a system for measuring, classifying, analyzing, and mapping spatial electrophysiological patterns and for guiding arrhythmia therapy.
b. Background Art
The human heart muscle routinely experiences electrical currents traversing its many surfaces and ventricles, including the endocardial chamber. Just prior to each heart contraction, the heart muscle is said to “depolarize” and “repolarize,” as electrical currents spread across the heart and throughout the body. In healthy hearts, the surfaces and ventricles of the heart will experience an orderly progression of a depolarization wave. In unhealthy hearts, such as those experiencing atrial arrhythmia, including for example, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter, the progression of the depolarization wave may not be so orderly. Arrhythmias may persist as a result of scar tissue or other obstacles to rapid and uniform depolarization. These obstacles may cause depolarization waves to repeat a circuit around some part of the heart. Atrial arrhythmia can create a variety of dangerous conditions, including irregular heart rates, loss of synchronous atrioventricular contractions, and stasis of blood flow, all of which can lead to a variety of ailments and even death.
Medical devices, such as, for example, electrophysiology (EP) catheters, are used in a variety of diagnostic and/or therapeutic medical procedures to correct such heart arrhythmias. Typically in a procedure, a catheter is manipulated through a patient's vasculature to a patient's heart, for example, and carries one or more electrodes that may be used for mapping, ablation, diagnosis, and/or to perform other functions. Once at an intended site, treatment may include radio frequency (RF) ablation, cryoablation, lasers, chemicals, high-intensity focused ultrasound, etc. An ablation catheter imparts such ablative energy to cardiac tissue to create a lesion in the cardiac tissue. This lesion disrupts undesirable electrical pathways and thereby limits or prevents stray electrical signals that lead to arrhythmias. As readily apparent, such treatment requires precise control of the catheter during manipulation to, from, and at the treatment site, which can invariably be a function of a user's skill level.
Before or during an ablation procedure, however, a user must measure and diagnose these undesirable electrical pathways and regions of arrhythmia “breakout.” An electrogram, used to help identify these regions, is any record of change in electric potential over time, often obtained by placing an electrode directly on or near the surface of the heart tissue. To acquire electrograms, conventional techniques include point-by-point methods of recording changes in electrical potential. These changes in potential may then be mapped onto a corresponding model of an anatomical structure. In other words, these methods enable the creation of electrocardiographic maps by navigating one or more catheters around an area of interest and collecting electrogram and spatial localization data from one spot to the next and then mapping the collected data accordingly.
A depolarization wave is detected on a signal from catheters to create maps such as Local Activation Time (LAT) and Peak to Peak (PP) voltage maps. In addition to being laborious and time consuming, these methods assume that a mapped electrogram is the result of only one depolarization. As a result, additional depolarizations, which commonly occur in complex arrhythmias, are not represented. Still further, due to the sequential nature of data acquisition, each electrogram of interest must then be time-aligned with a fixed fiducial reference.
Thus, conventional techniques and the resulting maps are not without drawbacks. As a further example, one map that is often created is a complex fractionated atrial electrogram (CFE) map. One type of CFE map documents mean cycle length or activation interval over a one to eight second period. A primary limitation of this type of CFE map is with its lack of specificity. Although any given electrogram may demonstrate CFE potentials, the underlying causes of the complex fractionated activity are unclear. And while the presence of complex fractionated activity suggests underlying anisotropy of conduction, this type of CFE map yields no direct information relating to underlying wavefront propagation patterns.
Accordingly, the inventors herein have recognized a need for improved systems and methods for acquiring a multitude of electrograms at the same time, and for a system that can provide a user with spatial maps that enable the user to view electrophysiological patterns and to determine the underlying causes of various arrhythmias that will minimize and/or eliminate one or more of the deficiencies in conventional systems.